As diagnosis is unsatisfactory, so is treatment. Usually all we can do is to treat symptoms; and by the time disease has advanced to the point of becoming externally noticeable, it has usually gone beyond the reach of medical treatment. It must also be remembered that drugs vary very much in their action in different families of animals. Nux vomica will not kill the gallinaceous birds of North America, and Tenant says that in Ceylon the hornbill feeds on the fruit of strychnos nux vomica. The pigeon is immune to opium. The _Felidæ_ are said to be unusually susceptible to carbolic acid; veratrum viride is harmless to sheep and elk, but poisonous to the horse; dogs can take with impunity large quantities of cyanide of potassium. These statements are true when the drugs are administered by mouth—the usual way of giving them to wild animals. The action may be different if the drugs are administered intravenously or subcutaneously. Variations in effect when they are administered by mouth are often due to chemical variations in the digestive secretions. It is probable that the action of cyanide of potash on dogs depends on the amount of hydrochloric acid in the digestive tract. When worms or their eggs are found in the stools vermifuges are used, and with some animals especially liable to infestation by intestinal worms, periodic doses of vermifuges are given as a prophylactic. Turpentine is given to the zebra at fixed intervals for the round worm; santonin, male fern and areca nut to the carnivora for the various worms that are so common in the intestinal tracts of these animals. The work of the Laboratory of Pathology is throwing light on the subject of diagnosis, and though from the character of the clinical material diagnosis can never be as satisfactory as in the human, yet we may fairly hope for improvement. Prophylaxis is our chief reliance, and always will be. DISEASE IN CAPTIVE WILD MAMMALS AND BIRDS SECTION I INTRODUCTION “We have also parks and enclosures of all sorts, of beasts and birds; which we use not only for view and rareness, but likewise for dissections and trials, that thereby we may take light what may be wrought upon the body of man.”